Apparatus for cooling oil of refrigerant compressors



July 27, 1954 F. H. HIEATT ET AL APPARATUS FOR COOLING OIL OF' REFRIGERANT COMPRESSORS Filed June 4, 1951 Patented July 27, 1954 UNITED S'E'TZS saisie OFFECE APPARATUS Fon CooLING on. or REFRIGERANT ooMPREssoRs Application June 4, 1951, Serial No. 229,725

1l Claims.

This invention has to do with apparatus for cooling oil of refrigerant compressors and it is a general object of the invention to provide apparatus that is eiiicient, dependable and highly effective.

In refrigerating apparatus where low temperatures are to be produced it is common to employ compressors in series so that there is a low pressure compressor and a high pressure compressor, and these compressors are usually conventional cylinder and piston type mechanisms each with a crank case employed as an oil reservoir. It is common in such apparatus for the oil to become mingled with the refrigerant and in some cases it is separated out by means of an oil separator and returned to the lubricating system While in other cases it is allowed to remain in the refrigerant and be carried around in the refrigerating system. Where high pressures are involved andthe compressors are operating at high capacity, the lubricating oil becomes heated and it is desirable that provision be made for cooling it.

It is a general object of the present invention to lprovide apparatus handling refrigerant by means of compressors wherein the crank cases of the compressors are interconnected so that lubricating oil circulates between them and is cooled in the course of such circulation.

Another object of this invention is to provide apparatus. handling a refrigerant by means of compressors and in which refrigerant compressed by the compressors is utilized as a medium for cooling oil required in the compressors.

It is a further object of the invention to provide apparatus of the general character referred to in which a sub-cooler is incorporated in the supply line handling the compressed refrigerant, which sub-cooler utilizes refrigerant from the supply line to effect the sub-cooling of the refrigerant that is handled by the line, the refrigerant drawn from the supply line being further utilized as an agent to cool the oil of the compressors.

In the refrigera'ting system including the present invention there is a refrigerating unit at which the refrigerant is utilized. A return line from the unit returns the expanded refrigerant to the intake of a primary compressor. A delivery line delivers the refrigerant from the outlet -of the primary compressor to the intake of the secondary compressor and a delivery line handles the refrigerant from the outlet of the secondary compressor to a heat exchanger. From the heat exchanger the cooled compressed refr. frigerant is handled by a receiver and a supply line conducts the refrigerant from the receiver to the unit where the refrigerant is used. The compressors are of the cylinder and piston type with crank cases handling or carrying lubricant. The system may be such that the lubricant is carried throughout the system in the refrigerant or an oil separator can be employed by the Secondary compressor and the heat exchanger and the oil conducted therefrom to one of the crank cases. A by-pass, thermally controlled, supplies refrigerant from the supply line to the line delivering refrigerant from the primary compressor to the secondary compressor.

A breather connection is provided between the crank cases above the level of lubricant therein, and a flow line connects the crank cases below the level of the lubricant. A cooling means is provided to cool the lubricant handled by the iow line and the medium used in this means is preferably refrigerant from the supply line, which is finally exhausted into the line conducting lubricant from the primary compressor to the secondary compressor. Where a sub-cooler is used in the supply line refrigerant drawn from the supply is handled by an expansion valve which may be thermostatically controlled and after-operating in the sub-cooler it operates in the oil cooler and is finally exhausted into the delivery line between the compressors.

The various objects and features of our invention will be fully understood from the following detailed description of a typical preferred form and application of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a diagrammatic View of a typical and simple form of refrigerating system in which the present invention is incorporated, and Fig. 2 is an enlarged detailed sectional view showing a construction that may be employed in the oil cooling means.

The refrigerating system embodying the invention and as shown throughout the, drawings involves, generally, a refrigerating unit A at which refrigerant is utilized, as for cooling a compartment of chest B. A primary or low pressure compressor C receives refrigerant exhausted from* the unit vA and a delivery line D conducts refrigerant from compressor C to a secondary or high pressure compressor E. A delivery line E' conducts refrigerant from the compressor E to a heat exchanger or cooler G from which the refrigerant is deliveredto a receiver H. A supply line J conducts refrigerant from the receiver H to the unit A and a thermally controlled bypass means K utilizes refrigerant from the supply means to cool the refrigerant delivered to the compressor E. In the case illustrated the compressors C and E are reciprocating mechanisms with crank cases carrying lubricant and a breather connection L connects the crank cases while a now connection M likewise connects the crank cases. A cooling means O is provided to cool lubricant handled by the flow connection M and may utilize refrigerant employed in a subcooler P provided in the ow line J.

The unit A illustrated to utilize the refrigerant handled by the system may be any suitable apparatus or equipment, as circumstances require. In the drawings we have shown an expansion valve It receiving refrigerant from the supply line J and delivering it to a coil EI, the valve being under control of a thermally responsive unit I2 connected to the valve by an operating means or connection I3. The outlet from the coil El is connected to an exhaust line I that extends to the intake of the primary or low pressure compressor C.

The low pressure compressor C is shown as being of the ordinary or conventional type wherein a cylinder block i5 is carried on a crank case I in which lubricant is maintained at a level Il. The lubricant handled by compressor C is delivered to the delivery line D which extends from compressor C to the intake of compressor E which, like compressor C, has a cylinder block I5 and a crank case it in which a lubricant level Il is maintained.

The delivery line F conducts compressed refrigerant from the compressor E to the intake of heat exchanger G indicated diagrammatically as a coil type mechanism but which may, in practice, be any suitable form or type of heat exchange apparatus. The heat exchanger G delivers the cooled refrigerant to the receiver l-I. The receiver holds a suitable supply of refrigerant and delivers the refrigerant to the supply line J which is shown as extending to the unit A.

ln the particular case illustrated a sub-cooler is provided in the supply line J and is indicated as including a jacket 3e through which the refrigerant is conducted while a cooling agent is circulated through a duct 3l within the jacket. The bypass means K is provided as a means for cooling refrigerant between the compressors and in the case illustrated it is shown as involving a bypass duct lil under control of a regulating valve QI. `A thermostatic unit 42 responsive to the temperature of refrigerant supplied to the secondary compressor controls an operating means 3 for the valve l I The present invention provides a mounting means 5t supporting the compressors C and E so that the lubricant in the crank cases has a common level. A breather connection L is provided between the crank cases above the liquid level and the flow connection lVl is a duct between the crank cases below the liquid level. It has been found in practice that compressors related as above described serve to circulate or pump lubricant with the result that in an arrangement such as is shown in the drawings there is circulation in the flow comiection M. Where an oil separator S is provided in the line F, as H shown in Fig. l, the lubricant will circulate in the direction indicated by the arrow. Where the system is such that the lubricant is carried throughout the system in the refrigerant the circulation or flow is usually in the opposite direction. it is to be understood, however, that in carrying out the invention, should it be found necessary or desirable to supplement or accelerate normal flow, such as will occur in the connection M, a suitable pump may be provided for this purpose, driven either by one of the compressors or provided with an independent power means, as circumstances require.

The cooling means O` is provided in connection with the flow connection M and serves to cool lubricant handled by the connection M. ln the case illustrated the means involves a chest til interposed on the connection M so that the lubricant handled by the connection flows therethrough. A cooling coil is provided in the chest 't8 and a suitable lubricant is circulated through the coil. ln the preferred form of the invention the refrigerant, utilized in the cooler P where a sub-cooler is included in the system, can be used to advantage in the cooling coil 5l. ln the case illustrated a line 'Eil connects into the supply line J ahead of the sub-cooler to draw refrigerant from the supply line. An expansion valve l! is provided in the line lil and delivers lubricant to the duct 3l so that it cools the refrigerant as it passes through the jacket 3B. An extension "II or the line 'lo continues from the sub-cooler to the coil Gi in the chest t!) and an exhaust line 'E2 from the discharge end of coil 6I A conducts the expanded refrigerant to the line D connecting the compressors C and E. Through this arrangement a small amount of refrigerant drawn from the supply line J is eiciently utilized to pre-cool or sub-cool the refrigerant before it reaches unit A, and this same small amount of refrigerant is used to cool the oil or lubricant required by the compressors. The exhausting lubricant, after having operated through the subcooler and cooling means O, is utilized to cool the initiallycompressed refrigerant being conducted to the high pressure compressor E.

ln the form of the invention illustrated a power line 3G operates motors 9c that drive the compressors, the motors being under control of switches 9i and the elements 42 and 43 of means l are electrical elements energized from the line il@ through a transformer T under control of a switch 95.

From the foregoing description it will be noted that the present invention provides a refrigerating system wherein the crank cases of the compressors are interconnected so that there is circulation of lubricant between the compressors and it provides for effective cooling of the circulating lubricant to the end that the compressors are maintained in operation under efficient working conditions. It is important to note that with the arrangement provided by the invention the cooling means O is entirely external of the compressors, that is, it is free of any cooling devices or elements within the compressors themselves, and furthermore, it is entirely free of water jackets or other like elements subject to leakage or failure in a manner to cause contamination either of the refrigerant or of the lubricant.

Having described only a typical preferred form and application of our invention, we do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to ourselves any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims.

Having described our invention, we claim:

l. A refrigeration system including, a refrigs my! erant handling unit, a primary refrigerant compressor receiving refrigerant from said unit, a secondary refrigerant compressor handling the output of the primary compressor, each compressor having a lubricant carrying crank case, a heat exch-anger receiving the output of the secondary compressor, and a supply line conducting refrigerant from the exchanger to said unit, a sub-cooler in the supply line employing refrigerant from the supply line, a flow connection passing lubricant between the crank cases, and lubricant cooling means cooling the lubricant handled by the connection, said cooling means including a chest in said flow connection through which thel lubricant passes, and a refrigerant line extending from said sub-cooler and through said chest.

2. A refrigeration system including, a refrigerant handlingV unit, a primary refrigerant compressor receiving refrigerant from said unit, a secondary refrigerant compressor handling the output of the primary compressor, each compressor having a lubricant carrying crank case, a heat exchanger receiving the output of the secondary compressor, and a supply line conducting refrigerant from. the exchanger to said unit, a sub-cooler in the supply line employing refrigerant from the supply line, a flow connection passing lubricant between the crank cases, and lubricant cooling means cooling the lubricant handled by the connection, said cooling means including a chest in said flow connection through which the lubricant passes, and a refrigerant line extending from said sub-cooler and through said chest, said refrigerant line delivering the refrigerant to the suction side of the secondary compressor.

3. A refrigeration system including, a refrigerant handling unit, a primary refrigerant compressor receiving refrigerant from said unit, a secondary refrigerant compressor, a delivery line conductiong the output of the primary compressor to the secondary compressor, each compressor having a lubricant carrying crank case, a heat exchanger receiving the output of the secondary compressor, and a supply line conducting refrigerant passed by the exchanger to said unit, a sub-cooler in the supply line employing refrigerant from the supply line, a flow connection passing lubricant between the crank cases, and lubricant cooling means cooling the lubricant handled by the connection including a refrigerant line extending from said sub-cooler to said delivery line and a chest interposed in said refrigerant line and surrounding said flow connection.

4l. A refrigeration system including, a refrigerant handling unit, a primary refrigerant compressor receiving refrigerant from said unit, a secondary refrigerant compressor handling the output of the primary compressor, a delivery line conducting the output of the primary compressor to the secondary compressor each compressor having a lubricant carrying crank case, a heat exchanger receiving the output of the secondary compressor, and a supply line conducting refrigerant passed by the exchanger to said unit, a iiow connection passing lubricant between the crank cases, lubricant cooling means including a duct surrounding the connection and receiving refrigerant from said supply line for cooling the lubricant handled by the connection including a refrigerant line extending from said sub-cooler to said delivery line and a chest interposed in said refrigerant line and surrounding said flow connection, and. a-by-'p'assv frigerant from the primary compressor to thcsecondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crankV case, a flow connection between the crank cases, and means cooling lubricant handled by the flow connection, said lubricant cooling means including a refrigerant line connected between the-supply line and said delivery line, and a chest in said refrigerant line and surrounding ysaid now connection.

6. In a refrigeration system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting refrigerant from the primary compressor tothe secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a lubricant separator between the secondary compressor and the heat exchanger delivering lubricant to the crank case of the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a flow connection between the crank cases, and means cooling lubricant handled by the now connection, said lubricant cooling means including a refrigerant line connected between the supply line and said delivery line, and a chest in said refrigerant line and surrounding said flow connection.

7. In a refrigeration system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting refrigerant from the primary compressor to the secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a flow connection between the crank cases, a sub-cooler in the supply line employing refrigerant from the supply line, and means cooling lubricant handled by the flow connection, said lubricant cooling means including a refrigerant line connected between said sub-cooler and said delivery line, and a chest in said refrigerant line surrounding said ow connection.

8. In a refrigeration system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting refrigerant from the primary compressor to the secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a sup-ply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a flow connection between the crank cases, and means cooling lubricant handled by the flow connection and employing refrigerant from the supply line and including a refrigerant line connected between said supply line, and a chest in said refrigerant line, said chest having a duct surrounding said ow connection and through which the refrigerant passes.

9. In a refrigerating system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting rerigerant from the primary compressor to the secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a flow connection between the crank cases, and means cooling lubricant handled by the flow connection and including a chest in said flow connection through which the lubricant passes, and a refrigerant line extending between the supply line and the delivery line and passing through said chest.

10. In a reirigerating system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting refrigerant from the primary compressor to the secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a flow connection between the crank cases, and means cooling refrigerant handled by the now connection and including a chest in said iiow connection through which the lubricant 8 passes, a refrigerant line extending between the supply line and the delivery line and passing through said chest, and an expansion Valve in the refrigerant line.

11. In a refrigerating system, a refrigerant handling unit, a primary compressor receiving refrigerant exhausted from said unit, a secondary compressor, a delivery line conducting refrigerant from the primary compressor to the secondary compressor, a heat exchanger receiving refrigerant from the secondary compressor, a supply line handling refrigerant from the exchanger and conducting it to the said unit, each compressor having a lubricant handling crank case, a ow connection between the crank cases, and means cooling refrigerant handled by the ow connection and including a chest in said ow connection through which the lubricant passes. and a refrigerant line extending between the supply line and the delivery line, said refrigerant line including a coil disposed in said chest.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,042,394 Gay May 26, 1936 2,178,100 Gygax Oct. 31, 1939 2,246,244 Consley June 1'7, 1941 2,322,874 Neeson et al June 29, 1943 2,391,200 Allen Dec. 18, 1945 2,418,962 Zwickl Apr. 15, 1947 2,424,010 Young July 15, 1947 

